Dinosaur

The Natural Reactor. Some two biUion years ago, uranium had a much higher (ca 3%) fraction of U than that of modem times (0.7%). There is a difference in half-hves of the two principal uranium isotopes, U having a half-life of 7.08 x 10 yr and U 4.43 x 10 yr. A natural reactor existed, long before the dinosaurs were extinct and before humans appeared on the earth, in the African state of Gabon, near Oklo. Conditions were favorable for a neutron chain reaction involving only uranium and water. Evidence that this process continued intermittently over thousands of years is provided by concentration measurements of fission products and plutonium isotopes. Usehil information about retention or migration of radioactive wastes can be gleaned from studies of this natural reactor and its products (12). 

Mesozoic Triassic 245 Myr Continents begin to drift apart. Early dinosaurs first mammals gymnosperms become dominant diversification of marine invertebrates. Moss extinction at end of period (ca. 75% of all species disappear)... 

Jurassic 195 Myr Two large continents form Laurasia (north) and Gondwana (south). Dinosaurs diversify first birds and mammals evolve gymnosperms dominate terrestrial vegetation ammonites radiate into diverse forms... 

Fig. 1.2 Reptiles Present in early groups ( ) of reptiles and mammals (+), absent in dinosaurs, persistent in only one archaic order (Tuataras, Rhynchocephalia) (after MacLean, 1990).

The remaining reptiles are monosmic, i.e. they are MOS-dependent with no functional accessory system. They derive from a secondarily aquatic group of Mesozoic dinosaurs, whose survivals are now represented by Crocodiles, Alligators and Caimans (Howes, 1891 Saint Girons, 1976). In these, the loss of accessory olfaction may have been part of a pre-adaptive trend. Genomic comparisons with the avian OR repertoires could provide some clues on AOS history in their living relatives. 

Some have left behind them traces of elements rare on Earth, such as iridium. The detection of traces of iridium from a large meteorite has led to a proposal that major extinction of species on Earth, namely the dinosaurs, could be due to the meteorite impact, causing chemical, light and temperature fluctuations, i.e. global climate changes, though this proposal is not universally accepted. 

The main problem with organic analyses from archaeological remains is their state of conservation. The question to be answered is whether any organic materials can be preserved over centuries or millennia. Many authors have proven that in certain conditions, preservation is possible [Evershed etalA992, Regert et al. 2003]. The question is of course very relevant in the case of dinosaur remains. In the case of preservation of organic materials, ToF-SIMS is well suited for such a study, because samples are very small and... 

Figure 1.6 Impact frustration (a) the Chicxulub crater, seen as a three-dimensional gravity map, thought to be responsible for the extinction of the dinosaurs (b) the cratered surface of the Moon. (Reproduced from photos by courtesy of NASA)...

Impact frustration A process typified by the extinction of the dinosaurs where the Earth s surface may have been sterilised of all life forms by the impact of a large meteorite or comet... 

Impact frustration The collision of a large meteorite with a planet that results in the extinction of some or all species on the planet, causing the sterilisation of life. An example would be the extinction of the dinosaurs. 

We were not able to determine exactly the length of time associated with the deposition of the clay layer. Instead the laboratory studies on the chemical and physical nature of the Cretaceous-Tertiary boundary led to the theory that an asteroid collision with the earth was responsible for the extinction of many forms of life including the dinosaurs. 

Ps = time since dinosaurs were last in their prime (31.7 million years ago)... 

Commercial representatives are the JEOL HXl 10/HXl lOA (EBEB, Eig. 4.30), the JEOL MStation-T (BEBE), or the Micromass AutospecT (EBEBE). As industrial laboratories are governed by high-throughput and other economic aspects, modem TOF/TOE, QqTOE and FT-ICR instmments have almost replaced these impressing dinosaurs weighing some 4-5 tons and having about 3 x 5 m footprint. Numerous custom-built four-sector instmments are still operated in laboratories devoted to gas phase ion chemistry. [102]... 

The extinction of the dinosaurs had one enduring consequence for us mammals we took over as important players among the living organisms on Earth. While the dinosaurs reigned, the mammals were bit players on the stage of life. If dinosaurs had survived, mammals might have continued to be of minor importance on Earth. 

Extraordinarily, fragments of the protein of connective tissue known as collagen have recently been extracted from bones of Tyrannosaurus rex. The primary structure of these fragments strengthens the suggestion that birds are our closest extant relatives to dinosaurs. This finding is certain to set off a determined effort to recover additional protein material from ancient fossils. 

An interesting story as to how most of the iridium appeared on Earth was explained recently by scientists who discovered a thin layer of iridium in the sediments that were laid down in the Earth s crust at the end of the Cretaceous period. This was a period about 65 million years ago when meteors and asteroids crashed into the Earth. These extraterrestrial bodies contained a high percentage of iridium. Dust from the impact spread around the Earth and blocked the sun for months, resulting in the extinction of many plants and animals, including the dinosaurs. This extensive dust cloud also deposited a thin coat of the element iridium that was contained in the fiery bolides. 

Witmer, L. M. (2001). Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293,850-854. 

Kolodny Y, Luz B, Navon O (1983) Oxygen isotope variations in phosphate of biogenic apatites, 1, Eish bone apatite - rechecking the rules of the game. Earth Planet Sci Lett 64 393 04 Kolodny Y, Luz B, Sander M, Clemens WA (1996) Dinosaur bones fossils or pseudomorphs The pitfalls of physiology reconstruction from apatitic fossils, Palaeogeogr PalaeocUmatol Palaeoecol 126 161-171... 

Cancer is the uncontrolled growth of abnormal cells. It is as old as the existence of animals— cancers are found even in dinosaur bones. Approximately 110 types of cancer have been characterized. In particular, breast cancer (second only to lung cancer in terms of fatality rate) strikes one in eight women and there are approximately 200,000 annual incidents in the United States alone. Twenty-five percent of women with breast carcinoma will even-mally die from their disease. The current arsenal of treatment for breast cancer includes... 

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